After completing and signing it please return the form to us in the envelope .A. provided

问题补充：

After completing and signing it, please return the form to us in the envelope .

A. provided

B. providing

C. having provided

D. provide

答案：

(答案→)A. provided

B. providing

C. having provided

D. provide

解析：句意：表格填完之后，请将其放入为您提供的信封中，返还给我们。动词provide与其逻辑主语envelop是被动关系，所以用过去分词作后置定语。